Considering safety, convenience, or recognition efficiency, biological recognition becomes the main way. Biological recognition can be achieved by using sensing devices. The sensing devices include capacitive type, thermal type, optical type, or the like. No matter what kind thereof, the biological sensing devices are typically fabricated on silicon chips.
Recently, the concept of biological recognition is further applied into portable electronic products, such as smart phones. For the smart phones in the market today, the biological (such as fingerprints, palm, or face) recognition means that is mainly used in the smart phones of various companies is capacitor fingerprint sensing device. Since the capacitor biological sensing device is needed to be fabricated on silicon chips, a space must be reserved on the surfaces of a smart phone for arranging the sensing area for biological recognition. It influences the aesthetic experience or usage convenience. In addition, the process for forming the open space must be added into the manufacturing processes. The manufacturing cost and/or process complexity may be increased. Further, the cost of using the silicon chips is rather high.
As such, research and improvement of fingerprint sensing means, particularly of the biological sensing means applicable in portable electronic products, have continued.